fix(anpr): sliding poll window so a car arriving mid-loop isn't lost

A loop started by a far/early car would (a) give up before the REAL car settled at
the barrier, and (b) swallow the real car's pushes (the #polling guard dropped them).
So a confident-but-wrong far-car plate could win, or the intended car get debounced
out after the loop ended — wrong car acted on, right car blocked.

Fix: a push that JOINS a running loop now EXTENDS the deadline (lastPush +
ANPR_POLL_WINDOW_MS) instead of being dropped, capped at start + ANPR_POLL_MAX_MS
(30s) so a continuously-busy lane can't slide forever. Each tick still pulls a FRESH
frame, so the loop tracks whoever is at the barrier NOW, not the car that started it.
Per-camera sliding deadline in #pollDeadline (cleared with #polling in finally).

+1 test (push mid-poll keeps the loop alive past the initial deadline); 171 server
tests green. New knob ANPR_POLL_MAX_MS documented in the komodo env reference + the
two concurrency guards written up in lane-presence-and-anpr-entry.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

komodo/.env.komodo.example

@@ -73,9 +73,11 @@ WS_ALLOWED_ORIGINS=
 #                                    #   read below this is ignored (falls back to card/QR).
 # ANPR_DEBOUNCE_MS=12000             # same plate/camera within this = one presentation
 # ANPR_POLL_MS=1000                  # poll-until-confident: re-pull a fresh frame every N ms
-# ANPR_POLL_WINDOW_MS=8000           # ...for up to this long while the car sits at the
-#                                    #   barrier. RAISE if a slow barrier means the car
-#                                    #   waits >8s before the plate reads clean.
+# ANPR_POLL_WINDOW_MS=8000           # ...for this long AFTER THE LAST vehicle push (sliding:
+#                                    #   a car arriving mid-loop extends it). RAISE if a slow
+#                                    #   barrier means the car waits >8s before reading clean.
+# ANPR_POLL_MAX_MS=30000             # hard ceiling on one loop from start (so a continuously
+#                                    #   busy lane can't slide the window forever)
 
 # ════════════════════════════════════════════════════════════════════════════
 # VISION CONTAINER env (the Python ANPR service — its OWN process, prefix VISION_)